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Observations of flowering phenology in Concord, Massachusetts, USA, 1963-1993

Cite this dataset

Miller-Rushing, Abraham; Primack, Richard; Ellwood, Elizabeth (2021). Observations of flowering phenology in Concord, Massachusetts, USA, 1963-1993 [Dataset]. Dryad.


Phenology plays a vital role in understanding the impacts of climate change on plants. Observing and recording the dates that plants are in flower, over periods of years and decades, can elucidate patterns in how plants respond to warming temperatures, shifting precipitation regimes, and other effects of a changing climate. Long-term records of plant phenology are difficult to find. It is often the case that these records do not originate from scientific research studies but instead are the product of an individual’s interest in observing natural phases in their local environment. Pennie Logemann (1918-2011) was a resident of Concord, Massachusetts, United States and a landscape designer. From 1963-1993 she recorded the flowering times of plants in her woodland garden, resulting in an invaluable dataset of wildflower and shrub phenology. These plants were primarily local native plants, but included some non-native species as well.  Most likely her garden contained a mixture of species occurring naturally on her property and species planted deliberately.

Logemann’s records have been analyzed in compilation with observations made by Henry David Thoreau and contemporary researchers in a study of recent climate change in Concord. The dataset provided here includes flowering phenology records for 71 species over 30 years (discontinuous for most species) at a single location. We encourage the use of these data in further studies of plant phenology and hope they may provide encouragement for others to record and share their phenology data.


Logemann’s methods involved regular surveys of her property where she recorded the dates that species were in flower. Her motivation for doing so was to inform her garden designs, ensuring a continuous floral display. Logemann shared the data directly with Miller-Rushing and Primack and these data were used in their 2008 publication. The data provided here are the original, raw dates and have not been processed.

Usage notes

The dataset includes genus and species along with common name of each plant species. Each year has an “s” and an “e” value, representing start and end dates of flower. Logemann was not explicit in her definition of start and end, but these values have been interpreted as the date when the first open flower was observed (start) and the last date that a fresh flower was still open (end). Missing values are indicated with NA.